2011 Mercedes GL450 A/C problem . OBDI scanner said " 9304 M13 heating water circulation pump open circuit

My A/C blows hot air for a moment then blow cold few minutes and then hot again and cold, eventually blow hot.

Refilled freon, replaced refrigerant pressure sensor, replace auxiliary water pump still blow hot air.

OBDI scanner still said "9304 M13 heating water circulation pump open circuit".

Is there auxiliary water pump (heating water circulation pump) relay or fuse?

Please advice.

 

God Bless,